Several different approaches to the conceptual analysis of causation are guided by the idea that a cause is something that makes a difference to its effects. These approaches seek to elucidate the concept of causation by explicating the concept of a difference-maker in terms of better-understood concepts. There is no better example of such an approach than David Lewis’ analysis of causation, in which he seeks to explain the concept of a difference-maker in counterfactual terms. Lewis introduced his counterfactual theory of causation with these words: 'We think of a cause as something that makes a difference, and the difference it makes must be a difference from what would have happened without it. Had it been absent, its effects—some of them, at least, and usually all—would have been absent as well.' (Lewis 1973b: pp. 160-1) According to Lewis, a cause c makes a difference to an effect e in the sense that if the cause c had not occurred, the effect e would not have occurred either. All we shall see in section 2, Lewis’ theory says there is more to the concept of causation than this counterfactual condition. Lewis is on the right track, I think, in saying that we think of a cause as something that makes a difference and that this thought is best explicated in terms of counterfactual concepts. However, I shall argue that the particular way in which Lewis spells out the concept of a cause as difference-maker is unsatisfactory. For Lewis’ articulation of this concept is distorted by a specific metaphysical assumption: specifically, that causation is an absolute relation, specifiable independently of any contextual factors. The distortion induced by this assumption is reflected in the undiscriminating manner in which his theory generates countless causes for any given effect. However, commonsense judgement is much more discriminating about causes than Lewis’ theory. Accordingly, I claim that Lewis' analysis faces the problem of profligate causes and I outline some specific problem cases in section 3..